This invention relates to silver oxide for use as a positive electrode active material in silver oxide cells, a process for producing the same and a galvanic cell using such silver oxide as a positive electrode active material.
The prior art in this field is found in the following references: Unexamined Published Japanese Patent Application No.53219/1973, 53221/1973 and 53222/1973 which specify the pore volume of a silver oxide positive electride active material per unit volume and its cell density; Unexamined Published Japanese Patent Application No.111956/1982 which teaches the effectiveness of porous silver oxide for discharge characteristics; and Unexamined Published Japanese Patent Application No.51469/1983 which teaches an improvement in moldability that is achieved by granulation with a binder.
These patents individually describe the desirable characteristics of the silver oxide for use in cells; however, no single silver oxides proposed by these patents satisfy the requirements of all characteristics but they have had the following defects:
(1) in the case of using the porous silver oxide, if an organic binder is employed with a view to improving the discharge characteristics, the pores in the silver oxide particles are plugged by the binder and the characteristics of the porous silver oxide are not fully exhibited; PA1 (2) if the addition of the binder is reduced, the strength of the granules decreases so much that they will break as a result of handling in the molding step and the flowability of the powder will eventually vary to deteriorate its meterability: and PA1 (3) the conventional silver oxide powder is not specified in terms of the size of primary particles and contains fines (.ltoreq.5 .mu.m) which do harm to the efficiency of mass production by getting into the clearance of pelletizing dies or sticking to the punches during molding.